 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal;

 import java.util.ArrayList ;
 import java.util.Iterator ;
 import java.util.List ;

 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IExtension;
 import org.eclipse.core.runtime.dynamichelpers.IExtensionTracker;
 import org.eclipse.jface.action.IMenuManager;
 import org.eclipse.jface.viewers.ISelection;
 import org.eclipse.jface.viewers.ISelectionProvider;
 import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.ui.IWorkbenchPart;

 /**
  * This manager is used to populate a popup menu manager with actions
  * for a given type.
  */
 public class ObjectActionContributorManager extends ObjectContributorManager {
     private static ObjectActionContributorManager sharedInstance;

     /**
      * PopupMenuManager constructor.
      */
     public ObjectActionContributorManager() {
         super();
         loadContributors();
     }

     /**
      * Contributes submenus and/or actions applicable to the selection in the
      * provided viewer into the provided popup menu.
      *
      * @param part the part being contributed to
      * @param popupMenu the menu being contributed to
      * @param selProv the selection provider
      * @return whether anything was contributed
      */
     public boolean contributeObjectActions(IWorkbenchPart part,
             IMenuManager popupMenu, ISelectionProvider selProv) {
         // Get a selection.
 ISelection selection = selProv.getSelection();
         if (selection == null) {
             return false;
         }

         // Convert the selection into an element vector.
 // According to the dictionary, a selection is "one that
 // is selected", or "a collection of selected things".
 // In reflection of this, we deal with one or a collection.
 List elements = null;
         if (selection instanceof IStructuredSelection) {
             elements = ((IStructuredSelection) selection).toList();
         } else {
             elements = new ArrayList (1);
             elements.add(selection);
         }

         List contributors = getContributors(elements);
        
         if (contributors.isEmpty()) {
             return false;
         }

         // First pass, add the menus and collect the overrides. Prune from the
 // list any non-applicable contributions.
 boolean actualContributions = false;
         ArrayList overrides = new ArrayList (4);
         for (Iterator it = contributors.iterator(); it.hasNext();) {
             IObjectActionContributor contributor = (IObjectActionContributor) it.next();
             if (!isApplicableTo(elements, contributor)) {
                 it.remove();
                 continue;
             }
             if (contributor.contributeObjectMenus(popupMenu, selProv)) {
                 actualContributions = true;
             }
             contributor.contributeObjectActionIdOverrides(overrides);
         }
         
         // Second pass, add the contributions that are applicable to
 // the selection.
 for (Iterator it = contributors.iterator(); it.hasNext();) {
             IObjectActionContributor contributor = (IObjectActionContributor) it.next();
             if (contributor.contributeObjectActions(part, popupMenu, selProv,
                     overrides)) {
                 actualContributions = true;
             }
         }
         return actualContributions;
     }

     /**
      * Returns the shared instance of this manager.
      * @return the shared instance of this manager
      */
     public static ObjectActionContributorManager getManager() {
         if (sharedInstance == null) {
             sharedInstance = new ObjectActionContributorManager();
         }
         return sharedInstance;
     }

     /**
      * Loads the contributors from the workbench's registry.
      */
     private void loadContributors() {
         ObjectActionContributorReader reader = new ObjectActionContributorReader();
         reader.readPopupContributors(this);
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.core.runtime.dynamicHelpers.IExtensionChangeHandler#addExtension(org.eclipse.core.runtime.dynamicHelpers.IExtensionTracker, org.eclipse.core.runtime.IExtension)
      */
     public void addExtension(IExtensionTracker tracker, IExtension addedExtension) {
         IConfigurationElement[] addedElements = addedExtension.getConfigurationElements();
         for (int i = 0; i < addedElements.length; i++) {
             ObjectActionContributorReader reader = new ObjectActionContributorReader();
             reader.setManager(this);
             reader.readElement(addedElements[i]);
         }
     }
 }

